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Strange pan behaviour

Hello,

A strange behaviour happened a few times. I explain:
I was drawing with pencil tool (I don't think the tool makes the difference) in a zoomed and rotated canvas.

I needed to pan the canvas to show an out-of-screen area of the drawing but... Both with the move tool or the space-key + pen drag happened that when I touched the tablet with the pen to start panning, the drawing disappeared, like there were applied an enormous drag, but I just touched the tabled surface.

This behaviour keeps appearing until I reset the canvas rotation. After this operation all went ok. This behaviour happened sometimes, like some specific canvas rotations can distort the pan function. Nothing on the drawing was lost, just an erroneous pan is performed.

Well, I managed to reproduce this behaviour a few times but it's not deterministic due the fact that the canvas rotator has not a numeric input (note that it's not a critique).
I could not reproduce the behaviour in a normal drawing session, so I looked for a more mechanical procedure.

I can suggest you a procedure but not guarantee that you can reproduce the behaviour at first try.

I suspect that the malfunction is related to the algorithm that should keep the canvas inside the screen.

1. Create a canvas screen size (mine is 1280x1024 but i suspect it doesn't matter)
2. Set a 50% zoom factor on the view
3. Pan the canvas to the leftmost of the screen.
4. Rotate the canvas a few degrees (5-10) counterclockwise (but i suspect that the rotation direction is indifferent)
5. Go to step 3 an repeat until the canvas disappear

Following this procedure I reproduced the effect 30% of times. I'm sorry I cannot be more precise.

Another behaviour I noticed in a drawing session is the following. Sometimes, after a few zooming (to 400+%) and rotations, the zoomed canvas cannot fully pan. I mean, if I zoom the canvas to, say 400%, i cannot pan it so I can fully scroll the entire surface of the canvas. It looks like the algorithm that keeps the canvas inside the screen thinks that the canvas is smaller than that it really is, with the result that the panning operation is stopped prematurely to an invisible boundary. This happens with zoomed canvas and in a non deterministic fashion. Also resetting the view with the D key does not solve the trouble: once zoomed again, the behaviour reappears. Creating a new Canvas solves the problem.